Concentrated sulfuric acid (H2SO4) scarification of balloonvine (Cardiospermum halicacabum L.) for 3 h reduced balloonvine seed coat thickness by 25%, and resulted in increased water absorption and maximum germination. Germination of balloonvine occurred at temperatures of 15 to 40 C with optimum germination occurring at 35 C. Intact balloonvine seed was more sensitive to simulated moisture stress than soybean [Glycine max (L.) Merr. ‘Bragg’]. No balloonvine germination occurred at osmotic potentials of −2 bars and less with intact seeds. Balloonvine seed with seed coats removed germinated at osmotic potentials of −8 bars. Maximum emergence of balloonvine occurred at the 1- and 3-cm depths with limited emergence at a depth of 12 cm.
